Selective multicast ethernet tag extension for optimal source driven multicast forwarding

ABSTRACT

A networking environment includes a first node and a second node configured as Ethernet Virtual Private Networking (EVPN) peers on an EVPN subnet that is coupled to a Layer 3 VPN over a core network. The first node receives a first multicast join request from a third node in the core network, the first multicast join request including a source address and multicast group address of a source of a multicast stream. The first node determines that the source address and the multicast group address for the source are behind the EVPN subnet at the second node. The first node sends to the second node, a control plane join request message that includes a receiver identifier that identifies the third node as a receiver of the multicast stream, the receiver identifier enabling the second node to forward the multicast stream directly into the core network to the third node.

TECHNICAL FIELD

The present disclosure relates to multicast forwarding in communicationnetworks.

BACKGROUND

An Ethernet Virtual Private Network (EVPN) fabric is useful for multipledeployments scenario. One such scenario is distributing multicasttraffic, which is often high bandwidth traffic. Optimal forwarding ofmulticast traffic in an EVPN fabric helps avoid any unnecessary trafficflows in the core network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams showing existing operations in a networktopology in which a multicast source is behind an Ethernet VirtualPrivate Networking (EVPN) fabric and receivers are behind a Layer 3 (L3)network segment.

FIG. 2 is a diagram of a network topology in which a first EVPN peer isconfigured to send to a second EVNP peer a control plane join requestmessage that includes information identifying the egress node associatedwith a multicast join request, according to an example embodiment.

FIG. 3 is a diagram illustrating a format of the control plane joinrequest message, according to an example embodiment.

FIG. 4 is a diagram similar to FIG. 2, and illustrating on example ofthe information identifying the egress node in the control plane joinrequest message, according to an example embodiment.

FIG. 5 is a diagram of the network topology of FIGS. 2 and 4, andshowing data plane forwarding of data packets of a multicast streamusing source-driven multicast routing information appended to the datapackets, according to an example embodiment.

FIG. 6 is a diagram similar to FIG. 2, but showing control planeoperations for different requests made to the same multicast source,according to an example embodiment.

FIG. 7 is a diagram illustrating data plane operations for the scenariodepicted in FIG. 6, according to an example embodiment.

FIG. 8 is a flow chart depicting control plane operations performed by afirst EVPN peer that receives a multicast join request via core networkand sends a control plane join request message to a second EVPN peerwhere the multicast source resides, according to an example embodiment.

FIG. 9 is a flow chart depicting data plane operations performed by asecond EVPN peer that receives a control plane join request message froma first EVPN peer, according to an example embodiment.

FIG. 10 is a hardware block diagram of a network device configured toperform the control plane operations and data plane operations of anEVPN peer node, according to an example embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

Techniques are provided for use in a networking environment thatincludes at least a first node and a second node configured as EthernetVirtual Private Networking (EVPN) peers of each other on an EVPN subnetthat is coupled to a Layer 3 VPN over a core network. In one embodiment,a method performed by the first node comprising. The first node receivesa first multicast join request from a third node (e.g., an egress node)in the core network, the first multicast join request including a sourceaddress and multicast group address of a source of a multicast stream.The first node determines that the source address and the multicastgroup address for the source are behind the EVPN subnet at the secondnode. The first node sends to the second node, a control plane joinrequest message that includes a receiver identifier that identifies thethird node as a receiver of the multicast stream, the receiveridentifier enabling the second node to forward the multicast streamdirectly into the core network to the third node.

In another embodiment, a method is provided that is performed by thesecond node. The second node receives from the first node, a controlplane join request message that includes the source address and themulticast group address of the source of the multicast stream and areceiver identifier that identifies the third node as a receiver of themulticast stream. The second node appends to data packets of themulticast stream, source-driven multicast routing information thatcauses data plane routing of the multicast stream in the core network tothe third node. The second node forwards the data packets with thesource-driven multicast routing information appended thereto, into thecore network.

Example Embodiments

Networking systems that involve multicast forwarding have employedmechanisms by which the receiver builds a multicast tree towards thesource of the multicast traffic. Other multicast tree buildingmechanisms involve source-based construction of the multicast treetoward the receiver. There are multiple protocols known to build amulticast tree. One such protocol is, for example, the Bit IndexExplicit Replication (BIER) protocol.

The BIER protocol is a forwarding paradigm that is useful to forward andreplicate multicast packets through a network. In BIER, the egressrouter is given an identifier, and the ingress router includes in thepackets identifier(s) of the egress router(s) to which a multicaststream should be forwarded. Packets are forwarded hop-by-hop using aspecial header that contains the identifier and which is embedded in thepackets. Routers in the network build a special forwarding table toforward/replicate packets using the BIER header. BIER allows for sendingas many multicast flows as needed without having to track state in thecore network that includes intervening routers/switches between theingress and egress routers that are on the edge of the core network.

[or] Reference is first made to FIG. 1A. FIG. 1A illustrates an exampleof a network 100 in which a multicast source is behind an EthernetVirtual Private Networking (EVPN) fabric and receivers are behind aLayer 3 (L3) network segment. Specifically, the network 100 includesprovider edge (PE) nodes 102(1), 102(2), 102(3) and 102(4), denoted PE1,PE2, PE3, and PE4, respectively. The PE nodes 102(1), 102(2), 102(3) and102(4) are configured to communicate over a L3 Virtual Private Network(L3VPN) 104 via a L3 core network (core network) 106.

In addition, PE nodes 102(1) and 102(3) are configured as EVPN peerswith each other, as shown at 110. There may be two or more PE nodes thatare configured as EVPN peers in the network 100. Two EVPN peer nodes isjust an example. There is a bridge domain (BD) between PE nodes 102(1)and 102(3) as shown at 112(1) and 112(3) to enable Selective MulticastEthernet Tag (SMET) techniques. In other words, PE nodes 102(1) and102(3) are in the same bridge domain and there is an EVPN Layer 2 (L2)extension between them and to the core network 106. Moreover, PE node102(1) has a virtual interface, called an Integrated Router and Bridge(IRB) interface 114(1) and PE node 102(3) has an IRB interface 114(3)that enables a connection from the EVPN L2 extension to the L3 corenetwork 106.

The IRB interfaces 114(1) and 114(3) are configured with an InternetProtocol (IP) address. Since this is a Layer 2 extension, the PE nodes102(1) and 102(3) are on the same EVPN subnet, e.g., 192.168.1.0/24. Atthe Layer 3 EPVN side towards the core network 106, when the IRBinterfaces 114(1) and 114(3) send reachability information, they willnot send the exact host address, but instead send the prefix, e.g.,192.168.1.0/24 to indicate that the hosts in the subnet are behind PEnodes 102(1) or 102(3).

In one example, as shown in FIG. 1A, each of the PE nodes has a BIERidentifier (ID), if BIER is used in the network 100. PE node 102(1) hasBIER ID “0001” or bit-1, PE node 102(2) has BIER ID “0010” or bit-2, PEnode 102(3) has BIER ID “0100” or bit-3 and PE node 102(4) has BIER ID“1000” or bit-4. PE node 102(2) may include in the overlay join sent at124, its BIER ID “0010” as an egress BIER ID.

From a Layer 3 network point of view, the Layer 3 core network 106accepts communications, e.g., multicast join requests, over the BorderGateway Protocol BGP or other protocols, such as the Interior GatewayProtocol (IGP). If PE node 102(2) needs to reach any source addressbehind the prefix 192.168.1.0/24, PE node 102(2) can send a request toeither to PE node 102(1) or PE node 102(3).

The control plane operational flow associated with a multicast joinrequest in the example network topology of FIG. 1A is now described.

For example, at 120, PE node 102(2) receives from a receiver endpoint122 or other entity that is behind PE node 102(2), a multicast joinrequest, such as an Internet Group Management Protocol (IGMP) joinrequest, for a source 123 that is at source address 192.168.1.1 andgroup address 232.1.1.1. PE node 102(2) checks in a local IGMP table howto reach the source address for the multicast join request 120. Sinceonly prefix reachability in the L3VPN network 104 is provided to avoidhost route overpopulating tables in PE nodes, PE node 102(2) gets anEqual Cost Multi-Path (ECMP) path to reach this prefix (of the multicastjoin request). One next hop from PE node 102(2) is PE node 102(1) andthe other next hop is PE node 102(3). The reason that PE node 102(2)gets an ECMP path is that there is a Layer 2 extension for the samesubnet, and both of the IRBs 114(1) and 114(3) are advertising the sameprefix. Individual source address reachability is not available, butrather aggregate visibility is provided, i.e., a prefix. When PE node102(2) does a longest prefix match to the prefix of the source addressof the join request, the match will point towards PE node 102(1) or PEnode 102(2).

As an example, the longest prefix match that PE node 102(2) performspoints to PE node 102(1). At 124, PE node 102(2) sends an overlay joinrequest, denoted (S,G) for source address and group address of themulticast join request 120, via an L3VPN procedure, to PE node 102(1).

PE node 102(1) receives the overlay join (S,G) and determines that therequested source address is behind PE node 102(3). Using SMETtechniques, at 126, PE node 102(1) sends a SMET (S,G) request to PE node102(3) to pull the multicast traffic from PE node 102(3) since thesource 123 is behind PE node 102(3). This is the control plane flow.

Reference is now made to FIG. 1B for a description of the data planeoperational flow for the control plane scenario depicted in FIG. 1A.

At 130, PE node 102(3) sends the multicast traffic to its SMET peer, PEnode 102(1). In one example in which the BIER protocol is used, PE node102(1) does BIER encapsulation and appends to the traffic the BIER ID“0001” corresponding to PE node 102(1) when sending the multicasttraffic to PE node 102(1) via core network 106. When PE node 102(1)receives the traffic, PE node 102(1) sends it to PE node 102(2), at 132,and in so doing, appends the BIER ID “0010” to the traffic when sendingthe multicast traffic to PE node 102(2).

As shown in FIG. 1B, the traffic passes through the core network 106twice, once from PE node 102(3) to PE node 102(1) at 130, and then againfrom PE node 102(1) to PE node 102(2) at 132. This is because PE node102(2) does not know where the source 123 is precisely located.Likewise, PE node 102(3) does not know where the actual receiver is; PEnode 102(1) knows that. PE node 102(3) does not know from which entityPE node 102(1) is requesting the multicast traffic. This is theinformation which is missing and which causes the inefficient data planescenario in which the traffic is sent twice through the core network106.

There are many mechanisms by which a multicast source can determinewhere the traffic is to be directed. For example, BIER is asource-driven multicast technology where bits are provided at theingress of a network, e.g., core network 106 shown in FIGS. 1A and 1B,to indicate where the traffic is to go at the egress of the core network106. RSVP-TE is a core tree mechanism in which the ingress PE drives thetree building mechanism. In addition, controller driven multicast is atechnology in which a controller builds the complete forwarding tree(for example, Tree-Segment Identifier (SID)). Common among these threemechanisms is that the source drives the multicast forwarding anddelivery path to a set of (one or more) receivers. The solutionpresented herein uses these characteristics of source driven multicasttechnologies, now know or hereinafter developed, to achieve optimalforwarding of multicast traffic.

Reference is now made to FIG. 2. FIG. 2 shows the network 100 of FIGS.1A and 1B, but in which the EVPN peer nodes PE 102(1) and PE 102(3) areconfigured to perform operations to make the data plane routing oftraffic from PE node 102(3) much more efficient. The PE node 102(2)receives the multicast join request 120 from receiver endpoint 122 andPE node 102(2) forwards the request to PE node 102(1), in the samemanner as described above in connection with FIG. 1A. However, PE node102(1) sends a control plane join request message 200, such as a SMET(S,G) join request, to PE node 102(3). The control plane join requestmessage 200 includes one or more receiver identifier(s) of the one ormore egress node(s) that requested the multicast traffic. The form andcontent of the receiver identifier(s) may depend on the source-drivencore tree mechanism employed. For example, the receiver identifier(s)may be included as an extended community attribute of a SMET joinrequest, and may take the form of a bitmap that identifies the PEnode(s) that sent the request, such as a bitmap or bitmask formattedaccording to the BIER protocol, e.g., BIER ID 0010 for PE node 102(2).In other forms, the receiver identifier(s) may be edge node identifierinformation or a loopback address or identifier. A loopback address oridentifier is a type of IP address that is used to test thecommunication or transportation medium on a local network card and/orfor testing network applications. Data packets sent on a loopbackaddress are re-routed back to the originating node without anyalteration or modification.

FIG. 2 also shows a controller 128 that is coupled to the nodes102(1)-102(4). The controller 128 may communication with the PE nodes102(1)-102(4) for a variety of reasons. One such use case is where thecontroller 128 is configured to perform controller driven multicast bywhich the controller 128 builds the complete forwarding tree, asexplained above.

Turning to FIG. 3, a diagram is shown of an example of the control planejoin request message 200. In one example, the control plane join requestmessage 200 includes a, such as a SMET route definition 205 definedaccording to draft-ietf-bess-evpn-igmp-mld-proxy-04, together with aplurality of attributes 210(1)-210(n) that are defined in extendedcommunities, where one of these attributes, e.g., attribute 210(3),includes receiver identifier information to support the operationsdepicted in FIG. 2. The control plane join request message 200 shown inFIG. 3 is used to coordinate IGMP join state for a given bridge domainbetween PE nodes. The attribute 210(3) contains the aforementionedreceiver identifier(s), that is the identifier(s) of the egress node(s)to which the multicast traffic is to be forwarded.

Reference is now made to FIG. 4. FIG. 4 shows an example use case forthe operational flow of FIG. 2, where the BIER protocol is used in thecore network 106. In this case, the control plane join request message200 that PE node 102(1) sends to PE node 102(3) includes BIER bits, inan extended community field 210(3) depicted in FIG. 3, for example, forthe last hop router, or egress node, e.g., identifying PE node 102(2).In the example of FIG. 4, this would be BIER ID “0010”. Then, the PEnode 102(3) creates an IP multicast (source address, group address) tosource-driven multicast routing information mapping 220. For example,the mapping 220 indicates that the (S,G) multicast traffic is mapped toBIER ID “0010”.

Turning now to FIG. 5, the data plane operational flow is now described.PE node 102(3) receives data packets 300 for an IP multicast stream fromthe source 123. The PE node 102(3) uses the IP multicast (sourceaddress, group address) to source-driven multicast routing informationmapping 220 to append to the data packets 300 the source-drivenmulticast routing information 310 to cause data plane routing, via anoutgoing interface (OIF) of PE node 102(3) to the core network 106,ultimately to the appropriate egress PE node.

Specifically, using the mapping 220, PE node 102(3) providessource-driven multicast routing information (SDMI) 310 that PE node102(3) appends (e.g., adds a header or tag) to the data packets 300 fordata plane routing of the multicast stream into the core network 106, asshown at 315 in FIG. 5. In one example, the source-driven multicastrouting information 310 may take the form of a BIER ID (bitmask), whichin this example, is “0010”. The network entities in the core network 106build a special forwarding table to forward/replicate the traffic usingthe BIER ID to the PE node 102(2), which in turn forwards the datapackets 300 to the receiver endpoint 122. The packets of the multicaststream are forwarded hop-by-hop using the BIER ID, and each BIER ID isforwarded along the unicast shortest path first (SPF) path.

As clearly shown in FIG. 5, unlike the scenario depicted in FIG. 1B, thePE node 102(1) does not receive the multicast traffic from the PE node102(3). The PE node 102(1) sends the multicast traffic directly throughthe core network 106 to PE node 102(2).

Reference is now made to FIG. 6, which illustrates a two receiverexample of the techniques depicted in FIGS. 2-5. That is, in addition toreceiver endpoint 122 behind PE node 102(2) sending a multicast joinrequest 405 for source address 192.168.1.1 and group address 232.1.1.1,another receiver endpoint 400, behind PE node 102(4), sends a multicastjoin request for 192.168.1.1 and group address 232.1.1.13. PE node102(4) sends an overlay join request 410, on behalf of the join request405, into the core network 106. The overlay join request 410 landsdirectly at PE node 102(3), in this example.

In the example in which the BIER protocol is used, PE node 102(3)generates a IP multicast to source-driven multicast routing informationmapping 415 that indicates PE 102(2) and PE 102(4) are receivers for themulticast stream. For example, the IP multicast to source-drivenmulticast routing information mapping 415 is the BIER bitmask “1010”.

FIG. 7 shows the data plane operational flow for the example of FIG. 6.The PE node 102(3) obtains from the mapping 415, a SDMI 420. In oneexample, SDMI is BIER bitmask “1010” to indicate that PE 102(2) and PE102(4) are receivers of the data packets 300 of a multicast stream. PEnode 102(3) appends the SDMI 420 on the data packets 300 and forwardsdata packets 300 with the appended SDMI 420 into core network 106 via anOIF that is coupled to core network 106. The network entities in thecore network 106 interpret the BIER bitmask and forward the data packets300 through the network, as described above in connection with FIG. 5.However, in the example of FIG. 7, the BIER bitmask “1010” is decomposedinto its constituent parts at some point in the core network 106, wherethe data packets 300 that are sent to PE 102(2) carry the BIER ID “0010”as shown at 425 and the data packets 300 that are sent to PE 102(4)carry the BIER ID “100”, as shown at 430.

Reference is now made to FIG. 8. FIG. 8 illustrates a flow chart for amethod 500 performed by a first node in a network environment thatincludes the first node and a second node, where the first node and thesecond node are configured as EVPN peers to each other on an EVPN subnetthat is coupled to a Layer 3 VPN over a core network. Thus, method 500depicts control plane operations performed by an EVPN peer node thatreceives a multicast join request for a multicast source that is notlocal to that EVNP peer node, but is instead behind the other EVPN peernode.

The method 500 includes, at 510, the first node receiving a firstmulticast join request from a third node in the core network, the firstmulticast join request including a source address and multicast groupaddress of a source of a multicast stream. At 520, the method 500includes the first node determining that the source address and themulticast group address for the source are behind the EVPN subnet at thesecond node. At 530, the method 500 includes the first node sending tothe second node, a control plane join request message that includes areceiver identifier that identifies the third node as a receiver of themulticast stream, the receiver identifier enabling the second node toforward the multicast stream directly into the core network to the thirdnode.

The control plane join request message that the first node sends to thesecond node in operation 530 may be a SMET join request. The receiveridentifier may be included in an extension, attribute or extendedcommunity of the SMET join request.

The receiver identifier may be any one of: a bitmap that identifies thethird node, a loopback identifier, or edge node identifier information.In one embodiment, the bitmap is formatted in accordance with the BIERprotocol.

Turning to FIG. 9, a flow chart is shown for a method 600 performed by asecond node in a network environment that includes a first node and thesecond node, where the first node and the second node are configured asEVPN peers to each other on an EVPN subnet that is coupled to a Layer 3VPN over a core network. The first node has received a first multicastjoin request from a third node in the core network, and the firstmulticast join request includes a source address and multicast groupaddress of a source of a multicast stream. Thus, the method 600 depictsthe data plane operations performed by an EVPN peer node when sendingmulticast traffic into the core network.

The method 600 includes, at 610, the second node receiving from thefirst node a control plane join request message that includes a receiveridentifier that identifies the third node as a receiver of the multicaststream. At 620, the method 600 includes the second node appending todata packets of the multicast stream, source-driven multicast routinginformation that causes data plane routing of the multicast stream inthe core network to the third node. At 630, the method includes thesecond node forwarding the data packets with the source-driven multicastrouting information appended thereto, into the core network.

The method 600 may further include generating a mapping between thesource address and group address of the source to the source-drivenmulticast routing information. The appending operation 620 then takesthe source-driven multicast routing information from this mapping toappend it to data packets of the multicast stream for data plane routingin the core network to the third node.

As explained above, the source-driven multicast routing information mayinclude any one of: a bit mask according to the Bit Index ExplicitReplication protocol, a label or identifier according to the ResourceReservation Protocol-Traffic Engineering (RSVP-TE) protocol, or anidentifier according to a controller-driven multicast mechanism in whicha controller that is in communication with the first node and secondnode, builds a multicast forwarding tree. Thus, the techniques presentedherein may use a label of any mechanism type to tag onto the data toindicate a single tree from the source to the receiver(s). There is noneed to stitch together multiple trees that are built in the corenetwork.

As described above in connection with FIG. 7, the source-drivenmulticast routing information identifies the third node and a fourthnode as multicast receivers of the multicast stream and thesource-driven multicast routing information is configured to cause dataplane routing of the multicast stream from the second node into the corenetwork to the third node and to the fourth node of the core network,the fourth node having sent to the first node or to the second node asecond multicast join request for the multicast stream from the source.

Reference is now made to FIG. 10. FIG. 10 illustrates a block diagram ofa network device 700 that may be configured to serve as either of the PEEVPN peer nodes, such as PE node 102(1) or 102(3) depicted in FIGS. 2and 4-7. The network device 700 includes a controller 710, memory 712that stores control software 714 for the network device 700, and aplurality of line cards 716(1)-716(N). The controller 710 may be one ormore microprocessors and executes the control software 714 to performcontrol the network device 700.

The memory 712 may be read only memory (ROM), random access memory(RAM), magnetic disk storage media devices, optical storage mediadevices, flash memory devices, electrical, optical, or otherphysical/tangible memory storage devices. Thus, in general, the memory712 may comprise one or more tangible (non-transitory) computer readablestorage media (e.g., a memory device) encoded with software comprisingcomputer executable instructions and when the software is executed (bythe controller 710) it is operable to perform the operations describedherein.

Each line card 716(1)-716(N) includes, among other components, a linecard central processing unit (CPU) 720, routing table memory 722, one ormore routing Application Specific Integrated Circuits (ASICs) 724 andnetwork ports 726. The line card CPU 720 controls the respective linecard and is coupled to routing table memory 722 and the routing ASICs724. The routing table memory 722 stores routing entries used to routenetwork traffic via network ports 726. The network ports 726 send(egress) network packets into a network and receive (ingress) networkpackets from a network. The routing ASICs 724 perform the routingfunctions among the plurality of network ports 726 based on entries inthe routing table memory 722, and controls provided by the controller710. The routing control operations that are performed by an EVPN PEnode described herein may be performed by the controller 710 or by theline card CPU 720, or the routing ASICs 724 in one or more of the linecards 716(1)-716(N).

The control software 714 may include software instructions that, whenexecuted by the controller 710, cause the controller 710 to configureone or more of the line cards 716(1)-716(N) to perform the control planeand/or data plane operations of an EVN peer node described above inconnection with FIGS. 2-9.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment. However, itshould be appreciated that any particular program nomenclature herein isused merely for convenience, and thus the embodiments should not belimited to use solely in any specific application identified and/orimplied by such nomenclature.

Data relating to operations described herein may be stored within anyconventional or other data structures (e.g., files, arrays, lists,stacks, queues, records, etc.) and may be stored in any desired storageunit (e.g., database, data or other repositories, queue, etc.). The datatransmitted between entities may include any desired format andarrangement, and may include any quantity of any types of fields of anysize to store the data. The definition and data model for any datasetsmay indicate the overall structure in any desired fashion (e.g.,computer-related languages, graphical representation, listing, etc.).

It is to be understood that the software of the present embodiments maybe implemented in any desired computer language and could be developedby one of ordinary skill in the computer arts based on the functionaldescriptions contained in the specification and flow charts illustratedin the drawings. Further, any references herein of software performingvarious functions generally refer to computer systems or processorsperforming those functions under software control. The computer systemsof the present embodiments may alternatively be implemented by any typeof hardware and/or other processing circuitry.

The various functions of the computer or other processing systems may bedistributed in any manner among any number of software and/or hardwaremodules or units, processing or computer systems and/or circuitry, wherethe computer or processing systems may be disposed locally or remotelyof each other and communicate via any suitable communications medium(e.g., Local Area Network (LAN), Wide Area Network (WAN), Intranet,Internet, hardwire, modem connection, wireless, etc.). For example, thefunctions of the present embodiments may be distributed in any manneramong the test module, the network device, the various end-user/clientand server systems, and/or any other intermediary processing devices.The software and/or algorithms described above and illustrated in theflow charts may be modified in any manner that accomplishes thefunctions described herein. In addition, the functions in the flowcharts or description may be performed in any order that accomplishes adesired operation.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present embodiments may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Python, C++, or the like, and procedural programminglanguages, such as the “C” programming language, Python or similarprogramming languages. The computer readable program instructions mayexecute entirely on the user's computer, partly on the user's computer,as a stand-alone software package, partly on the user's computer andpartly on a remote computer or entirely on the remote computer orserver. In the latter scenario, the remote computer may be connected tothe user's computer through any type of network, including a local areanetwork (LAN) or a wide area network (WAN), or the connection may bemade to an external computer (for example, through the Internet using anInternet Service Provider). In some embodiments, electronic circuitryincluding, for example, programmable logic circuitry, field-programmablegate arrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the presented embodiments.

Aspects of the present embodiments are described herein with referenceto flowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to presentedembodiments. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variouspresented embodiments. In this regard, each block in the flowchart orblock diagrams may represent a module, segment, or portion ofinstructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In summary, in one embodiment, a method is provided for use in anetworking environment that includes at least a first node and a secondnode configured as Ethernet Virtual Private Networking (EVPN) peers ofeach other on an EVPN subnet that is coupled to a Layer 3 VPN over acore network, the method performed by the first node and comprising:receiving a first multicast join request from a third node in the corenetwork, the first multicast join request including a source address andmulticast group address of a source of a multicast stream; determiningthat the source address and the multicast group address for the sourceare behind the EVPN subnet at the second node; and sending to the secondnode, a control plane join request message that includes a receiveridentifier that identifies the third node as a receiver of the multicaststream, the receiver identifier enabling the second node to forward themulticast stream directly into the core network to the third node.

In another form, a method is provided for use in a networkingenvironment that includes at least a first node and a second nodeconfigured as Ethernet Virtual Private Networking (EVPN) peers of eachother on an EVPN subnet that is coupled to a Layer 3 VPN over a corenetwork, the first node having received a first multicast join requestfrom a third node in the core network, the first multicast join requestincluding a source address and multicast group address of a source of amulticast stream, the method performed by the second node andcomprising: receiving from the first node, a control plane join requestmessage that includes the source address and the multicast group addressof the source of the multicast stream and a receiver identifier thatidentifies the third node as a receiver of the multicast stream;appending to data packets of the multicast stream, source-drivenmulticast routing information that causes data plane routing of themulticast stream in the core network to the third node; and forwardingthe data packets with the source-driven multicast routing informationappended thereto, into the core network.

In another form, a system is provided comprising at least a first nodeand a second node configured as Ethernet Virtual Private Networking(EVPN) peers of each other on an EVPN subnet that is coupled to a Layer3 VPN over a core network; the first node is configured to: receive afirst multicast join request from a third node in the core network, thefirst multicast join request including a source address and multicastgroup address of a source of a multicast stream; determine that thesource address and the multicast group address for the source are behindthe EVPN subnet at the second node; and send to the second node, acontrol plane join request message that includes a receiver identifierthat identifies the third node as a receiver of the multicast stream,the receiver identifier enabling the second node to forward themulticast stream directly into the core network to the third node; thesecond node is configured to: receive the control plane join requestmessage; append to data packets of the multicast stream, source-drivenmulticast routing information that causes data plane routing of themulticast stream in the core network to the third node; and forward thedata packets with the source-driven multicast routing informationappended thereto, into the core network.

In yet another form, an apparatus that is to serve as a first node amongat least first and second nodes that are configured as Ethernet VirtualPrivate Networking (EVPN) peers of each other on an EVPN subnet that iscoupled to a Layer 3 VPN over a core network, the apparatus comprising aplurality of network ports and a controller, wherein the controller isconfigured to: obtain a first multicast join request received from athird node in the core network, the first multicast join requestincluding a source address and multicast group address of a source of amulticast stream; determine that the source address and the multicastgroup address for the source are behind the EVPN subnet at the secondnode; and generate a control plane join request message to be sent tothe second node, the control plane join request message including areceiver identifier that identifies the third node as a receiver of themulticast stream, the receiver identifier enabling the second node toforward the multicast stream directly into the core network to the thirdnode.

In yet another form, an apparatus is provided that is to serve as asecond node among at least first and second nodes that are configured asEthernet Virtual Private Networking (EVPN) peers of each other on anEVPN subnet that is coupled to a Layer 3 VPN over a core network, thefirst node having received a first multicast join request from a thirdnode in the core network, the first multicast join request including asource address and multicast group address of a source of a multicaststream, the apparatus comprising: a plurality of network ports and acontroller, wherein the controller is configured to: obtain a controlplane join request message received from the first node, the controlplane join request message including the source address and themulticast group address of the source of the multicast stream and areceiver identifier that identifies the third node as a receiver of themulticast stream; append to data packets of the multicast stream,source-driven multicast routing information that causes data planerouting of the multicast stream in the core network to the third node;and cause the data packets with the source-driven multicast routinginformation appended thereto to be forwarded into the core network.

In still another form, one or more non-transitory computer readablestorage media are provided, encoded with instructions that, whenexecuted by a processor of a network device that serves as a first nodeamong at least first and second nodes that are configured as EthernetVirtual Private Networking (EVPN) peers of each other on an EVPN subnetthat is coupled to a Layer 3 VPN over a core network, cause theprocessor to perform operations including: receiving a first multicastjoin request from a third node in the core network, the first multicastjoin request including a source address and multicast group address of asource of a multicast stream; determining that the source address andthe multicast group address for the source are behind the EVPN subnet atthe second node; and sending to the second node, a control plane joinrequest message that includes a receiver identifier that identifies thethird node as a receiver of the multicast stream, the receiveridentifier enabling the second node to forward the multicast streamdirectly into the core network to the third node.

In yet another form, one or more non-transitory computer readablestorage media are provided, encoded with instructions that, whenexecuted by a processor of a network device that serves as a second nodeamong at least first and second nodes that are configured as EthernetVirtual Private Networking (EVPN) peers of each other on an EVPN subnetthat is coupled to a Layer 3 VPN over a core network, the first nodehaving received a first multicast join request from a third node in thecore network, the first multicast join request including a sourceaddress and multicast group address of a source of a multicast stream,cause the processor to perform operations including: receiving from thefirst node, a control plane join request message that includes thesource address and the multicast group address of the source of themulticast stream and a receiver identifier that identifies the thirdnode as a receiver of the multicast stream; appending to data packets ofthe multicast stream, source-driven multicast routing information thatcauses data plane routing of the multicast stream in the core network tothe third node; and forwarding the data packets with the source-drivenmulticast routing information appended thereto, into the core network.

The descriptions of the various embodiments have been presented forpurposes of illustration, but are not intended to be exhaustive orlimited to the embodiments disclosed. Many modifications and variationswill be apparent to those of ordinary skill in the art without departingfrom the scope and spirit of the described embodiments. The terminologyused herein was chosen to best explain the principles of theembodiments, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. In a networking environment that includes atleast a first node and a second node configured as Ethernet VirtualPrivate Networking (EVPN) peers of each other on an EVPN subnet that iscoupled to a Layer 3 VPN over a core network, a method performed by thefirst node comprising: receiving a first multicast join request from athird node in the core network, the first multicast join requestincluding a source address and multicast group address of a source of amulticast stream; determining that the source address and the multicastgroup address for the source are behind the EVPN subnet at the secondnode; and sending to the second node, a control plane join requestmessage that includes a receiver identifier that identifies the thirdnode as a receiver of the multicast stream, the receiver identifierenabling the second node to forward the multicast stream directly intothe core network to the third node.
 2. The method of claim 1, whereinthe control plane join request message is a Selective Multicast EthernetTag (SMET) join request, and the receiver identifier is included in anextension, attribute or extended community of the SMET join request. 3.The method of claim 2, wherein the receiver identifier is any one of: abitmap that identifies the third node, a loopback identifier, or edgenode identifier information.
 4. The method of claim 3, wherein thebitmap is formatted in accordance with the Bit Index ExplicitReplication protocol.
 5. The method of claim 1, further comprising, atthe second node: appending to data packets of the multicast stream,source-driven multicast routing information that causes data planerouting of the multicast stream in the core network to the third node;and forwarding the data packets with the source-driven multicast routinginformation appended thereto, into the core network.
 6. The method ofclaim 5, further comprising, at the second node: generating a mappingbetween the source address and group address of the source to thesource-driven multicast routing information.
 7. The method of claim 5,wherein the source-driven multicast routing information includes any oneof: a bit mask according to a Bit Index Explicit Replication (BIER)protocol, a label or identifier according to a Resource ReservationProtocol-Traffic Engineering (RSVP-TE) protocol, or an identifieraccording to a controller-driven multicast mechanism in which acontroller that is in communication with the first node and second node,builds a multicast forwarding tree.
 8. The method of claim 5, whereinthe source-driven multicast routing information identifies the thirdnode and a fourth node as multicast receivers of the multicast streamand the source-driven multicast routing information is configured tocause data plane routing of the multicast stream from the second nodeinto the core network to the third node and to the fourth node of thecore network, the fourth node having sent to the first node or to thesecond node a second multicast join request for the multicast streamfrom the source.
 9. In a networking environment that includes at least afirst node and a second node configured as Ethernet Virtual PrivateNetworking (EVPN) peers of each other on an EVPN subnet that is coupledto a Layer 3 VPN over a core network, the first node having received afirst multicast join request from a third node in the core network, thefirst multicast join request including a source address and multicastgroup address of a source of a multicast stream, a method performed bythe second node comprising: receiving from the first node, a controlplane join request message that includes the source address and themulticast group address of the source of the multicast stream and areceiver identifier that identifies the third node as a receiver of themulticast stream; appending to data packets of the multicast stream,source-driven multicast routing information that causes data planerouting of the multicast stream in the core network to the third node;and forwarding the data packets with the source-driven multicast routinginformation appended thereto, into the core network.
 10. The method ofclaim 9, generating a mapping between the source address and groupaddress of the source to the source-driven multicast routinginformation.
 11. The method of claim 9, wherein the control plane joinrequest message is a Selective Multicast Ethernet Tag (SMET) joinrequest, and the receiver identifier is included in an extension,attribute or extended community of the SMET join request.
 12. The methodof claim 11, wherein the receiver identifier is any one of: a bitmapthat identifies the third node, a loopback identifier, or edge nodeidentifier information.
 13. The method of claim 9, wherein thesource-driven multicast routing information includes any one of: a bitmask according to a Bit Index Explicit Replication (BIER) protocol, alabel or identifier according to a Resource Reservation Protocol-TrafficEngineering (RSVP-TE) protocol, or an identifier according to acontroller-driven multicast mechanism in which a controller that is incommunication with the first node and second node, builds a multicastforwarding tree.
 14. The method of claim 9, wherein the source-drivenmulticast routing information identifies the third node and a fourthnode as multicast receivers of the multicast stream and thesource-driven multicast routing information is configured to cause dataplane routing of the multicast stream from the second node into the corenetwork to the third node and to the fourth node of the core network,the fourth node having sent to the first node or to the second node asecond multicast join request for the multicast stream from the source.15. A system comprising: at least a first node and a second nodeconfigured as Ethernet Virtual Private Networking (EVPN) peers of eachother on an EVPN subnet that is coupled to a Layer 3 VPN over a corenetwork; the first node is configured to: receive a first multicast joinrequest from a third node in the core network, the first multicast joinrequest including a source address and multicast group address of asource of a multicast stream; determine that the source address and themulticast group address for the source are behind the EVPN subnet at thesecond node; and send to the second node, a control plane join requestmessage that includes a receiver identifier that identifies the thirdnode as a receiver of the multicast stream, the receiver identifierenabling the second node to forward the multicast stream directly intothe core network to the third node; the second node is configured to:receive the control plane join request message; append to data packetsof the multicast stream, source-driven multicast routing informationthat causes data plane routing of the multicast stream in the corenetwork to the third node; and forward the data packets with thesource-driven multicast routing information appended thereto, into thecore network.
 16. The system of claim 15, wherein the control plane joinrequest message is a Selective Multicast Ethernet Tag (SMET) joinrequest, and the receiver identifier is included in an extension,attribute or extended community of the SMET join request.
 17. The systemof claim 16, wherein the receiver identifier is any one of: a bitmapthat identifies the third node, a loopback identifier, or edge nodeidentifier information.
 18. The system of claim 17, wherein the bitmapis formatted in accordance with the Bit Index Explicit Replicationprotocol.
 19. The system of claim 15, wherein the source-drivenmulticast routing information includes any one of: a bit mask accordingto a Bit Index Explicit Replication (BIER) protocol, a label oridentifier according to a Resource Reservation Protocol-TrafficEngineering (RSVP-TE) protocol, or an identifier according to acontroller-driven multicast mechanism in which a controller that is incommunication with the first node and second node, builds a multicastforwarding tree.
 20. The system of claim 15, wherein the source-drivenmulticast routing information identifies the third node and a fourthnode as multicast receivers of the multicast stream and thesource-driven multicast routing information is configured to cause dataplane routing of the multicast stream from the second node into the corenetwork to the third node and to the fourth node of the core network,the fourth node having sent to the first node or to the second node asecond multicast join request for the multicast stream from the source.